The present invention relates to a method for the clinical treatment of a plurality of malignant tumours, especially in solid form, in mammals by the administering of quinoline derivatives. Furthermore, the present invention relates to structurally novel quinoline derivatives, to methods for their preparation and to compositions containing them. The types of cancer that are especially inhibited by the quinoline derivatives of the present invention include, for example, breast cancers, colon cancers, Kaposi""s sarcoma, lung cancers, ovarian cancers, prostatic cancers, and skin cancers. More particularly, the present invention relates to quinoline derivatives suitable for treatment of and preventing the development of prostatic cancer, and for preventing and treatment of the metastases of prostatic cancer.
Solid tumours, primary or metastases consist of several types of cells where the tumour cells are the pivotal cell type and the driving force. When microtumours reach a certain size, the requirement of nutrition cannot be satisfied by plain diffusion. New vessels penetrate the tumour establishing a microenvironment providing the tumour with optimal nutrition for further proliferation and growth. This tumour induced angiogenesis, inducing proliferation, migration and differentiation of normal endothelial cells from nearby small blood vessels, is a prerequisite for the growth of solid tumours. In concordance the inhibition of angiogenesis results in an effective inhibition of growth of solid tumours.
Solid tumours spread by penetrating tissue borders and give rise to daughter cell colonies or metastases. Single tumour cells or small cell aggregates spread by the blood or the lymph system to distant sites. In this process the tumour cells are vulnerable and can be extinguished by natural killer (NK) cells, a distinct type of cytotoxic lymphocytes. Enhanced activity or an increased number of NK cells reduce or inhibit the metastasising process in solid tumour disease.
Prostatic cancer is a malignant tumour disease that spreads to distant sites as tumour metastases and comprises tumours with great dependence of neovascularisation. Prostatic cancer has long been a major affliction of men, and it is becoming more common and dangerous as the population ages. It is an adenocarcinoma that is second only to lung cancer in mortality. Prostate cancer currently accounts for about 35,000 deaths each year in the United States alone. To the present time, there are no effective preventive or treatment methods for prostatic cancer. When the cancer is in its early, hormone-dependent stage, it is commonly treated by orchiectomy or chemical castration. In the later stages of prostatic cancer, the disease becomes hormone-independent and metastasises widely, usually first into the skeleton. Treatment for advanced disease initially involves hormonal manipulations and palliative radiotherapy or treatment with cytostatic agents. These strategies have proven to be of marked clinical benefit in terms of symptomatic relief but there are no effective methods, which can put prostatic cancer into remission in that stage. The use of cytotoxic agents in the management of hormone-resistant advanced prostate cancer remains poorly defined. A few single agents have become xe2x80x9cstandard therapyxe2x80x9d, although demonstration of their efficacy, by contemporary standards, is lacking. Thus, prostatic cancer is not only relatively common, but is refractory to treatment once the disease crosses into the hormone-independent stage.
In U.S. Pat. No. 4,547,511 and in EP 59,698 some derivatives of N-aryl-1,2-dihydro-4-amino-1-alkyl-2-oxo-quinoline-3-carboxamide and N-aryl-1,2-dihydro-4-hydroxy-1-alkyl-2-oxo-quinoline-3-carboxamide are claimed as enhancers of cell-mediated immunity. Roquinimex (Merck Index 12th Ed., No. 8418; Linomide(copyright), N-methyl-N-phenyl-1,2-dihydro-4-hydroxy-1-methyl-2-oxo-quinoline-3-carboxamide) has been reported to have antitumour effects on Dunning R-3327 rat prostatic cancers (1).
Some 5-substituted N-aryl-1,2-dihydro-4-hydroxy-1-alkyl-2-oxo-quinoline-3-carboxamides effective in the treatment of diseases resulting from autoimmunity and pathologic inflammation are known from U.S. Pat. No. 6,077,851, U.S. Ser. Nos. 09/352,886 and 09/352,887.
Roquinimex, a compound with shown anti-angiogenic and pro NK lymphocyte activities also induce pro-inflammatory side effects in humans that was emphasised when treating patients with renal cell carcinoma (2). Roquinimex in this study was poorly tolerated, with 40% of the patients being withdrawn or having dose reductions due to adverse events, mostly influenza-like symptoms of myalgia, arthralgia and fatigue. Several cases of pericarditis and neuropathy were also observed.
Pro-inflammatory effects induced by roquinimex are efficiently monitored in the beagle dog. Roquinimex induces the beagle pain syndrome characterised by fever, myalgia, arthralgia as well as arteritis (3, 4).
A primary objective of the present invention is a method for the clinical treatment of a plurality of malignant tumours, especially in solid form, in mammals by the administration of quinoline derivatives. Another objective is to provide structurally novel quinoline derivatives, having a pharmacological profile that is distinguished by high potency in experimental models and low level of side effects. The types of cancer that are especially inhibited by these quinoline derivatives include, for example, breast cancers, colon cancers, Kaposi""s sarcoma, lung cancers, ovarian cancers, prostatic cancers, and skin cancers. More particularly, the present invention relates to quinoline derivatives suitable for the prevention of the development of malignant tumours, in particular prostatic cancers, and prevention and treatment of the metastases of malignant tumours, particularly of prostatic cancers. To increase the cure rate of metastatic malignant tumours, in particular of prostatic cancers, an effective therapy for malignant tumour cells, particularly androgen-independent prostatic cancer cells, is needed. The approach we have chosen is to inhibit the tumour-induced angiogenesis and to stimulate the host immune system to evoke/enhance an antitumour response. In the present invention, the ability of quinoline compounds to elicit an antitumour effect against an androgen-independent Dunning R-3327 AT-1 rat prostatic cancer was tested.
It has now surprisingly been found that the compounds of general formula (I) 
wherein
A is selected from OR41 and NR42 R43 wherein
R41 is selected from hydrogen and pharmaceutically acceptable inorganic cations, such as sodium, potassium and calcium, and organic cations such as monoethanolamine, diethanolamine, dimethylaminoethanol, morpholine and the like, and CORA wherein
RA is selected from alkyl and aryl groups, such as methyl, ethyl, n-propyl, iso-propyl, tert-butyl, neo-pentyl, phenyl, benzyl, phenethyl and the like;
R42 and R43 are the same and different and selected from hydrogen, methyl, ethyl, n-propyl, iso-propyl, n-butyl, cyclopropyl, cyclopentyl and cyclohexyl; or
R42 is selected from benzyl and phenethyl, optionally mono- or disubstituted by a group selected from methyl, iso-propyl, methoxy, fluoro, chloro, bromo, dimethylamino, trifluoromethyl and nitro and R43 is hydrogen; or
R42 and R43 together with the nitrogen to which they are bonded, form a 5- or 6xe2x80x2-membered ring; or
R42 is CORB wherein
RB is selected from alkyl and aryl groups, such as C1-C4-alkyl, phenyl, benzyl and the like, or
from xe2x80x94CH2N(CH3)2 and xe2x80x94CH1CH2CH2COOH; or
CORB is a 2-acyloxymethylbenzoyl group 
wherein
RC is selected from methyl, ethyl, phenyl and benzyl and the like; or
R42 is COORD wherein
RD is selected from C1-C4-alkyl, phenyl and benzyl; or
R42 is xe2x80x94CH2OCO-tert.-butyl; or
R42 is CONRFRG wherein
RF and RG are the same and different and are C1-C4-alkyl; or
R42 is CXNHRE wherein
X is selected from O or S and RE is selected from C1-C4-alkyl, C2-C4-alkyl functionalised with an tertiary amino group, and phenyl, optionally functionalised with a p-chloro group; or
R42 is CH2NRHRI wherein
RHand RI are the same and different and are C1-C4-alkyl or RH and RI together with the nitrogen to which they are bonded, form a morpholine ring; and
R43 is selected from hydrogen, methyl, ethyl and cyclopropyl;
R is selected from hydrogen, methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec.-butyl and allyl; with the proviso that R is not hydrogen when A is OR41;
Rxe2x80x2 is selected from hydrogen, methyl, methoxy, phenyl, fluoro, chloro, bromo, cyano, nitro, azido, trifluoromethyl, and OCHxFy,
xe2x80x83wherein
x=0-2,
y=1-3 with the proviso that
x+y=3;
and with the proviso that Rxe2x80x2 is not hydrogen when R is methyl and A is OR41;
Rxe2x80x3 is selected from hydrogen, fluoro and chloro, with the proviso that Rxe2x80x3 is selected from fluoro and chloro only when Rxe2x80x2 is selected from fluoro and chloro;
R5 is selected from hydrogen, methyl, ethyl, n-propyl, iso-propyl, methoxy, ethoxy, thiomethyl, thioethyl, thio-n-propyl, thio-iso-propyl, fluoro, chloro, bromo, trifluoromethyl, nitro, amino, dimethylamino and OCHxFy, and OCH2CHxFy,
xe2x80x83wherein
x=0-2,
y=1-3 with the proviso that
x+y=3 and
with the further provisos that R5 is not fluoro or amino when A is OR41; and that R5 is hydrogen only when A is NR42 R43 and Rxe2x80x2 is trifluoromethyl;
R6 is hydrogen; or
R5 and R6 taken together are methylenedioxy;
are unexpectedly effective and specific in the treatment of individuals suffering from advanced cancer.
The compounds of general formula (I) may exist in different tautomeric forms and all such forms where such forms exist are included herein. Also optical isomers and racemates of the compounds of general formula (I) where such forms exist are included herein.
In a preferred embodiment of the invention R5 is selected from methyl, ethyl, methoxy, ethoxy, thiomethyl, thioetyl, chloro, and bromo, or R5 and R6 taken together are methylenedioxy, A is selected from OR41 and NR42 R43, wherein R41 is selected from hydrogen and sodium, and wherein R42 and R43 are the same and different and selected from hydrogen, methyl and ethyl, R is selected from hydrogen, methyl, ethyl and n-propyl, especially methyl and ethyl, and Rxe2x80x2 is selected from hydrogen, para-methyl, -phenyl, -methoxy, -chloro, -trifluoromethyl and -azido, especially from methoxy, chloro, and trifluoromethyl when Rxe2x80x3 is hydrogen, and Rxe2x80x3 is selected from metaxe2x80x2- and para-fluoro provided that Rxe2x80x2 is ortho-fluoro.
The invention also discloses novel compounds of the general formula (Ixe2x80x2) 
wherein
R42 and R43 are the same and different and selected from hydrogen, methyl, ethyl, n-propyl, iso-propyl, n-butyl, cyclopropyl, cyclopentyl and cyclohexyl; or
R42 is selected from benzyl and phenethyl, optionally mono- or disubstituted by a group selected from methyl, iso-propyl, methoxy, fluoro, chloro, bromo, dimethylamino, trifluoromethyl and nitro and R43 is hydrogen; or
R42 and R43 together with the nitrogen to which they are bonded, form a 5- or 6-membered ring; or
R42 is CORB wherein
RB is selected from alkyl and aryl groups, such as C1-C4-alkyl, phenyl, benzyl and the like; or
from xe2x80x94CH2N(CH3)2 and xe2x80x94CH2CH2COOH; or
CORB is a 2-acyloxymethylbenzoyl group 
wherein
RC is selected from methyl, ethyl, phenyl and benzyl and the like; or
R42 is COORD wherein
RD is selected from C1-C4-alkyl, phenyl and benzyl; or
R42 is xe2x80x94CH2OCO-tert.-butyl; or
R42 is CONRFRG wherein
RF and RG are the same and different and are C1-C4-alkyl; or
R42 is CXNHRE wherein
X is selected from O or S and RE is selected from C1-C4-alkyl, C2-C4-alkyl functionalised with an tertiary amino group, and phenyl, optionally functionalised with a p-chloro group; or
R42 is CH2NRHRI wherein
RH and RI are the same and different and are C1-C4-alkyl or RH and RI together with the nitrogen to which they are bonded, form a morpholine ring; and
R43 is selected from hydrogen, methyl, ethyl and cyclopropyl;
R is selected from hydrogen, methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec.-butyl and allyl;
Rxe2x80x2 is selected from hydrogen, methyl, methoxy, fluoro, chloro, bromo, cyano, nitro, azido, trifluoromethyl, and OCHxFy,
xe2x80x83wherein
x=0-2,
y=1-3 with the proviso that
x+y=3,
Rxe2x80x3 is selected from hydrogen, fluoro and chloro, with the proviso that Rxe2x80x3 is selected from fluoro and chloro only when Rxe2x80x2 is selected from fluoro and chloro;
R5 is selected from hydrogen, methyl, ethyl, n-propyl, iso-propyl, methoxy, ethoxy, thiomethyl, thioethyl, thio-n-propyl, thio-iso-propyl, fluoro, chloro, bromo, trifluoromethyl, nitro, amino, dimethylamino and OCHxFy, and OCH2CHxFy 
xe2x80x83wherein
x=0-2,
y=1-3 with the proviso that
x+y=3 and
with the proviso that R5 is hydrogen only when and Rxe2x80x2 is trifluoromethyl,
R6 is hydrogen; or
R5 and R6 taken together are methylenedioxy;
or any tautomer, optical isomer or racemate thereof;
as well as novel compounds of the general formula (Ixe2x80x3) 
wherein
R is selected from methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec.-butyl and allyl;
R41 is selected from hydrogen and pharmaceutically acceptable inorganic cations, such as sodium, potassium and calcium, and organic cations such as monoethanolamine, diethanolamine, dimethylaminoethanol, morpholine and the like; and CORA wherein
RA is selected from alkyl and aryl groups, such as methyl, ethyl, n-propyl, iso-propyl, tert-butyl, neo-pentyl, phenyl, benzyl, phenethyl and the like;
Rxe2x80x2 is selected from hydrogen and phenyl;
Rxe2x80x3 is hydrogen;
R5 is methyl, ethyl, n-propyl, iso-propyl, methoxy, ethoxy, thiomethyl, thioethyl, thio-n-propyl, thio-iso-propyl, chloro, bromo, trifluoromethyl, dimethylamino and OCHxFy, and OCH2CHxFy 
xe2x80x83wherein
x=0-2,
y=1-3 with the proviso that
x+y=3 and;
with the further proviso that Rxe2x80x2 only is hydrogen when R5 is dimethylamino and R is different from methyl,
or any tautomer, optical isomer or racemate thereof.
Among the most preferred compounds are: N-ethyl-N-phenyl-1,2-dihydro-4-hydroxy-1,5-dimethyl-2-oxo-quinoline-3-carboxamide, N-ethyl-N-phenyl-1,2-dihydro-4-hydroxy-5-ethyl-1-methyl-2-oxo-quinoline-3-carboxamide, N-ethyl-N-phenyl-1,2-dihydro-4-hydroxy-5-methoxy-1-methyl-2-oxo-quinoline-3-carboxamide, N-ethyl-N-phenyl-1,2-dihydro-4-hydroxy-5-chloro-1-methyl-2-oxo-quinoline-3-carboxamide or its sodium salt, N-ethyl-N-phenyl-1,2-dihydro-4-hydroxy-5-bromo-1-methyl-2-oxo-quinoline-3-carboxamide, N-ethyl-N-phenyl-1,2-dihydro-4-hydroxy-5,6-methylenedioxy-1-methyl-2-oxo-quinoline-3-carboxamide, N-ethyl-N-phenyl-1,2-dihydro-4-hydroxy-5-dimethylamino-1-methyl-2-oxo-quinoline-3-carboxamide, N-ethyl-N-(3-fluoro-phenyl)-1,2-dihydro-4-hydroxy-5-chloro-1-methyl-2-oxo-quinoline-3-carboxamide, N-methyl-N-(4-chloro-phenyl)-1,2-dihydro-4-hydroxy-5-chloro-1-methyl-2-oxo-quinoline-3-carboxamide, N-methyl-N-(4-methyl-phenyl)-1,2-dihydro-4-hydroxy-5-chloro-1-methyl-2-oxo-quinoline-3-carboxamide, N-methyl-N-(4-phenyl-phenyl)-1,2-dihydro-4-hydroxy-5-chloro-1-methyl-2-oxo-quinoline-3-carboxamide, N-methyl-N-(2,4-difluoro-phenyl)-1,2-dihydro-4-hydroxy-5-chloro-1-methyl-2-oxo-quinoline-3-carboxamide, N-methyl-N-(2,5-difluoro-phenyl)-1,2-dihydro-4-hydroxy-5-chloro-1-methyl-2-oxo-quinoline-3-carboxamide, N-ethyl-N-(3-methoxy-phenyl)-1,2-dihydro-4-hydroxy-5-ethyl-1-methyl-2-oxo-quinoline-3-carboxamide, N-methyl-N-(2,4-difluoro-phenyl)-1,2-dihydro-4-hydroxy-5-methoxy-1-methyl-2-oxo-quinoline-3-carboxamide, N-methyl-N-(2,5-difluoro-phenyl)-1,2-dihydro-4-hydroxy-5-methoxy-1-methyl-2-oxo-quinoline-3-carboxamide, N-methyl-N-(4-trifluoromethyl-phenyl)-1,2-dihydro-4-hydroxy-5-methoxy-1-methyl-2-oxo-quinoline-3-carboxamide, N-methyl-N-(2,4-difluoro-phenyl)-1,2-dihydro-4-hydroxy-5,6-methylenedioxy-1-methyl-2-oxo-quinoline-3-carboxamide, N-methyl-N-(4-chloro-phenyl)-1,2-dihydro-4-hydroxy-1,5-dimethyl-2-oxo-quinoline-3 -carboxamide, N-methyl-N-(2,4-difluoro-phenyl)-1,2-dihydro-4-hydroxy-5-ethyl-1-methyl-2-oxo-quinoline-3-carboxamide, N-n-propyl-N-phenyl-1,2-dihydro-4-hydroxy-5-thiomethyl-1-methyl-2-oxo-quinoline-3-carboxamide, N-methyl-N-(4-chloro-phenyl)-1,2-dihydro-4-hydroxy-5-thiomethyl-1-methyl-2-oxo-quinoline-3-carboxamide, N-methyl-N-(4-trifluoromethyl-phenyl)-1,2-dihydro-4-hydroxy-5-thiomethyl-1-methyl-2-oxo-quinoline-3-carboxamide, N-methyl-N-(2,4-difluoro-phenyl)-1,2-dihydro-4-hydroxy-5-thiomethyl-1-methyl-2-oxo-quinoline-3-carboxamide, N-methyl-N-(2,5-difluoro-phenyl)-1,2-dihydro-4-hydroxy-5-thiomethyl-1-methyl-2-oxo-quinoline-3-carboxamide, N-methyl-N-(4-methoxy-phenyl)-1,2-dihydro-5-dimethylamino-4-hydroxy-1-methyl-2-oxo-quinoline-3-carboxyde, N-methyl-N-phenyl-4-amino-1,2-dihydro-1,5-dimethyl-2-oxo-quinoline-3-carboxamide, N-methyl-N-phenyl-4-amino-1,2-dihydro-5-methoxy-1-methyl-2-oxo-quinoline-3-carboxamide, N-methyl-N-phenyl-5-chloro-1,2-dihydro-4-(N-methylamino)-1-methyl-2-oxo-quinoline-3-carboxamide, N-methyl-N-phenyl-1,2-dihydro-1,5-dimethyl-4-(N-methylamino)-2-oxo-quinoline-3-carboxamide, N-methyl-N-phenyl-1,2-dihydro-5-methoxy-4-(N-methylamino)-1-methyl-2-oxo-quinoline-3-carboxamide, N-methyl-N-(4-trifluoromethyl-phenyl)-4-amino-1,2-dihydro-1-methyl-2-oxo-quinoline-3-carboxamide.
High crystal lattice energy of solid compounds results in poor solubility, e.g., in water. Hence, an approach to reduce this energy will result in improved aqueous solubility. The prodrug per se is an inactive species. A basal requisite for a prodrug approach is the reconversion of the prodrug to the parent drug in vivo. The prodrugxe2x80x94drug conversion may take place before, during or after absorption. The necessary conversion of prodrugs to the parent drug molecules in the body can take place by a variety of reactions. The most common prodrugs are those requiring a hydrolytic cleavage mediated by enzymatic hydrolysis. In other cases, drug molecules are regenerated from their prodrugs by biochemical reductive or oxidative processes.
Esters of drugs containing a hydroxyl function have been considered as prodrug types primarily from the fact that the organism is rich in enzymes capable of hydrolysing esters.
Compounds of the present invention contain an enolised carbonyl group as a prominent functional group. Under proper conditions, the enol form can be trapped by acylation of the enol group. Steric and electronic effects within the acyl group have a substantial influence upon both the aqueous and enzymatic rates of hydrolysis. Besides, physicochemical properties such as water-solubility, lipophilicity and dissolution rate can be modified for the parent compound.
Compounds of the present invention contain a 4-amino function. N-Acylation of amines to give activated amides may be a promising means of obtaining prodrug forms. 2-Hydroxymethylbenzamides undergo a cyclisation (lactonisation) in aqueous solution to give phtalide and free amine. Substitution of the two methylene hydrogen atoms of 2-hydroxymethylbenzamide with, for example, methyl and phenyl groups greatly affects the lactonisation rates. Also blocking the lactonisation by acylation of the 2-hydroxymethylbenzamides to give 2-acyloxymethylbenzamides affects the lactonization that must be preceded by hydrolysis of the ester grouping. Furthermore, the acylation allows control of the lipophilicity/hydrophilicity of the prodrug by the appropriate selection of the acyl group. The use of various carbamate derivatives as well as N-Mannich bases can also be considered as means to forming prodrugs.
The compounds of general formula (I) were assayed for their capacity to inhibit of growth of the Dunning R-3327 AT-1 tumour, a prostatic rat cancer. Roquinimex was used as positive treatment control and showed a 30% inhibition at 4 mg/kg.
The compounds of general formula (I) wherein A is NR42 R43 are prepared by the following method:
Method A 
The compounds of formula (Ixe2x80x2) may be prepared by known methods, for example, by reaction of 4-chloro-1,2-dihydro-2-oxo-quinoline-3-carboxamide derivative (X=Cl; II) known from U.S. Pat. No. 4,547,511 with an amino compound in a suitable solvent such as an alcohol, e.g., ethanol. All compounds had satisfactory 1H-NMR and mass spectra, although the NMR spectra were complicated due to presence of E and Z amide isomers. Only the major isomer is described by NMR-shifts below.
Method B 
The compounds of general formula (Ixe2x80x3) may be prepared by methods known from U.S. Pat. No. 6,077,851 and, for example, as shown above, by reaction of an ester derivative of the quinoline carboxylic acid with an aniline in a suitable solvent such as toluene, xylene and the like. General methods for preparation of the quinoline carboxylic acid ester derivatives of formula (III) are known from U.S. Pat. No. 4,547,511. N-alkylated anilines of formula (IV) are commercially available or known from literature, e.g., in Johnstone et al, J. Chem. Soc. 1969, 2223-2224. Compounds falling within the scope of formula (IV) may be prepared by methods, which are generally analogous to those of said literature.
The scope of the invention is as defined in the claims, which hereby are included by reference.
The following examples are intended to illustrate the invention without restricting the scope thereof.